Automated cooking machines, such as bread makers, have become increasingly popular. Another type of automated cooking machine is shown in U.S. Pat. Nos. 4,649,810; 4,779,522; 4,820,054; 4,942,807, all issued to the present inventor, the disclosures of which are incorporated by reference. This type of automated cooking machine permits ingredients to be added at different times, stirred and turned or flipped. One way to implement a stirring action is to use a simple planar stirrer to scrape the bottom of the pot in a circular fashion. The shape of the stirrer will cause the food ingredients to spread out or tumble over the top of the stirrer. However, the overall action is not a true turn and flip motion so that its effectiveness is compromised in many situations.
The two-axis turn and flip stirrer disclosed in, for example, U.S. Pat. No. 4,942,807 is an automated stirrer which will perform a true turn and flip function. However, in certain situations even the stirrer shown in this patent is not as effective as could be desired. This can occur when cooking a relatively small amount of an ingredient or when the cooking surface is extremely slippery, as could be caused by non-stick surface coating or the presence of a sufficient amount of water, oil or other liquid. In these situations, the stirrer can have a tendency to push the ingredients forward rather than turning and flipping the ingredients. The slippage will render the two-axis stirrer less effective than it is designed to be. Therefore, an effective two-axis stirrer also depends on sufficient surface friction developed at least in part by the total weight of the ingredients to be pushed, turned and flipped.
To solve the problem of ingredients being pushed forward rather than turning, the present inventor came up with another design disclosed in U.S. Pat. No. 5,535,665. An obstruction or blocking element was introduced to create a blocking motion to prevent the ingredient from being pushed forward by the turning spatula. The accumulation of blocked ingredients allowed the spatula to turn and flip the ingredients more effectively. If the ingredients are small relative to the size of the spatula, turning and flipping will be effective. If the thickness of the ingredients is larger than the width of the spatula, the turning will be less effective. Also thin and long ingredients such as noodles have tendency to whirl and tangle around the stirrer. Another occasional problem is food jammed between the spatula and the bottom of the cooking container or the obstruction element. Jamming can occur for several reasons. For example, an edge of the spatula might get caught on top of a large hard ingredient. While the drive mechanism can be clutched to prevent damage the machine, a very elaborate gearing and clutching arrangement may be necessary to release the jammed condition. Even so there will still be a small chance the food cannot be freed and require operator intervention. The stirrer assembly itself involves angle turning gears, shafts, a wiper and a spatula; it requires disassembly for cleaning and assembly for cooking.